Influenza A virus affects 10-20% of the world's population every year, causing 500,000 to 1,000,000 deaths. Aquatic birds are the primary biotic reservoir for all influenza viruses, and most of these birds are migratory. One of the major avian migratory paths in Asia is from Siberia to China. We have begun to isolate, identify, and enumerate influenza gene subtypes in arctic lakes in northeastern Siberia that are on the flight paths of a large number of migratory birds that fly south into China. We will follow any changes in progression of influenza subtypes in each of the lakes during summer, winter, and spring. We presently have summer water and winter ice samples from 2001, 2002, and 2003 and have detected influenza viruses in both types of samples. A study is proposed to expand the sampling sites in 2004-2005 and to assess the amounts and subtypes of virus (2001-2005) deposited in the summer by the birds, preserved in the ice during winter, and released from the ice during spring melting. The specific aims are: 1. To identify and enumerate subtypes of influenza A in water and ice from Siberian lakes which are in the flight path of migratory birds that fly south into China; 2. Assess the viability of such influenza A subtypes in the lake water and ice samples; 3. Determine the prevalence of such influenza A subtypes separately by year (2001-2005) and by season (summer water, winter ice, and spring water and ice); 4. Correlate the prevalence of influenza A subtypes in Asian water and ice with estimates of avian migratory populations and reported prevalence of human influenza. This will be the first study to monitor the concentrations of influenza subtypes in arctic lake water and ice, and to determine whether the water and ice are significant reservoirs for these pathogens. The study will provide information about the contribution of lakes to patterns of influenza spread, as well as the relationship between virus spread and time, weather, and other transmission indices. If the lake water and ice are significant reservoirs of influenza, then continued surveillance of arctic lakes may lead to another tool in the battle against this disease. [unreadable] [unreadable]